Muscle growth in adult humans results from muscle fibre hypertrophy. Hypertrophy is the result of an increased net muscle protein balance [ie. fractional muscle protein synthesic rate (FSR)-muscle protein degradation rate (MPD)]. Both FSR and MPD can be stimulated by heavy resistance exercise in humans. It is also known that amino acid transport is increased after resistance exercise. Further understanding of the factors influencing net protein balance may allow the ability to maximize FSR and minimize MPD, thus maximizing the rate and amount of muscle hypertrophy. Research is the area of resistance training and its effects on FSR and MPD is limited. Recent work from independent laboratories has shown that FSR was elevated after a bout of resistance training in humans. Net protein balance, although more positive, was stillnegative following resistance exercise in the fasted state.